Hi!
when you knit stripes that repeat a few rows higher, then you can "cable up" along the side (given that it is not a visible edge such as the button band, of course). Just twist the working yarn and the one or more colors that get carried are cought there. Much better than cutting.
once you are done with using a certain color for good or for a longer stretch: cut it and weave the ends. I am always careful not to pull that carried yarn too tight, since that may lead to contracted sides. just "casually" keep it there, like in stranding.